US 6887987 B1
Here we describe the molecular identification of a cDNA encoding a novel serine protease we have termed protease T. The deduced amino acid sequence encodes a prepro form of 290 amino acids, and its alignment with other well-characterized serine proteases indicates that it is a member of the S1 serine protease family. We have found that the protease T mRNA is expressed in stomach, testis, retina, fibroblasts, spinal cord, and several regions of the brain. Protease T mRNA is also found in leukocytes and in the Jurkat (ATCC TIB-152) T cell line. Thus, this protease is potentially involved in gastric, testicular, retinal, dematological, neurological/neurodegenerative and/or immunological disorders. The protease T gene maps to human chromosome 16p13.3 which is near the tryptase locus. Enzymatically active protease T, we have generated, is amenable to further biochemical analyses for the identification of physiological substrates and specific modulators.
1. An isolated and purified nucleic acid molecule that encodes serine protease T and has a nudeotide sequence set forth in SEQ.ID.NO.:1 or SEQ.ID.NO.:8.
2. The isolated and purified nucleic acid molecule of
3. The isolated and purified nucleic acid molecule of
4. An expression vector, wherein said vector contains a nucleic acid molecule having a nucleotide sequence set forth in SEQ.ID.NO.:1 or SEQ.ID.NO.:8 that encodes serine protease T having an amino acid sequence set forth in SEQ.ID.NO.:7 or SEQ.ID.NO.:9.
5. The expression vector of
6. The expression vector of
7. A recombinant host cell containing the expression vector of
8. The recombinant host of
9. The recombinant host of
10. A process for expression of serine protease T in a recombinant host cell, comprising:
(a) transferring an expression vector containing a nucleic acid molecule having a nucleotide sequence set forth in SEQ.ID.NO.:1 or SEQ.ID.NO.:8 that encodes serine protease T having an amino acid sequence set forth in SEQ.ID.NO.:7 or SEQ.ID.NO.:9 into suitable host cells; and
(b) culturing the host cells of step (a) under conditions which allow expression of the serine protease T from the expression vector.
This is a Divisional of prior application Ser. No. 09/386,653, filed 31 Aug. 1999 now U.S. Pat. No. 6,458,564.
Members of the trypsin/chymotrypsin-like (S1) serine protease family play pivotal roles in a multitude of diverse physiological processes, including digestive processes and regulatory amplification cascades through the proteolytic activation of inactive zymogen precursors. In many instances protease substrates with in these cascades are themselves the inactive form, or zymogen, of a “downstream” serine protease. Well-known examples of serine protease-mediated regulation include blood coagulation, (Davie, et al (1991). Biochemistry 30:10363-70), kinin formation (Proud and Kaplan (1988). Ann Rev Immunol 6: 49-83) and the complement system (Reid and Porter (1981). Ann Rev Biochemistry 50:433-464). Although these proteolytic pathways have been known for sometime, it is likely that the discovery of novel serine protease genes and their products will enhance our understanding of regulation within these existing cascades, and lead to the elucidation of entirely novel protease networks.
Proteases are used in non-natural environments for various commercial purposes including laundry detergents, food processing, fabric processing, and skin care products. In laundry detergents, the protease is employed to break down organic, poorly soluble compounds to more soluble forms that can be more easily dissolved in detergent and water. In this capacity the protease acts as a “stain remover.” Examples of food processing include tenderizing meats and producing cheese. Proteases are used in fabric processing, for example, to treat wool in order prevent fabric shrinkage. Proteases may be included in skin care products to remove scales on the skin surface that build up due to an imbalance in the rate of desquamation. Common proteases used in some of these applications are derived from prokaryotic or cukaryotic cells that are easily grown for industrial manufacture of their enzymes, for example a common species used is Bacillus as described in U.S. Pat. No. 5,217,878. Alternatively, U.S. Pat. No. 5,278,062 describes serine proteases isolated from a fungus, Tritirachium album, for use in laundry detergent compositions. Unfortunately use of some proteases is limited by their potential to cause allergic reactions in sensitive individuals or by reduced efficiency when used in a non-natural environment. It is anticipated that protease proteins derived from non-human sources would be more likely to induce an immune response in a sensitive individual. Because of these limitations, there is a need for alternative proteases that are less immunogenic to sensitive individuals and/or provides efficient proteolytic activity in a non-natural environment. The advent of recombinant technology allows expression of any species' proteins in a host suitable for industrial manufacture.
Here we describe the molecular identification of a cDNA encoding a novel serine protease we have termed protease T. The protease T cDNA sequence predicts a preproprotease T polypeptide of 290 amino acids, and its alignment with other well-characterized serine proteases clearly indicates that it is a member of the S1 serine protease family.
Enzymatically active protease T is amenable to further biochemical analyses for the identification of physiological substrates and specific modulators. Modulators of Protease T are potentially useful as therapeutic agents in the treatment of diseases associated with the immune system, including but not limited to immune cell function. In addition, expression of protease T in certain regions of the brain as well as the testis and stomach, suggests that modulators of protease T function could be used to treat disorders effecting these tissues. Purified protease T can be manufactured as a component for formulation of compositions for cleansing agents, food processing, fabric processing, laundry detergents and skin care products.
The recombinant DNA molecules coding for protease T, and portions thereof, are useful for isolating homologues of the DNA molecules, identifying and isolating genomic equivalents of the DNA molecules, and identifying, detecting or isolating mutant forms of the DNA molecules.
FIG. 1—The nucleotide (SEQ.ID.NO.:1) and amino acid sequence (SEQ.ID.NO.:7) of the novel protease T cDNA is shown.
FIG. 2—The phylogenetic tree of the protease T amino acid sequence relative to other S1 serine proteases is shown.
FIG. 3—PCR-based tissue distribution indicates that the protease T mRNA is restricted. Autoradiograms of gels are shown with the position of the protease T specific PCR product, as detected by the hybridization of a labeled nested probe, which was resolved following electrophoresis from the free probe (F.P.). The cDNA libraries of tissues and cell lines analyzed are as indicated.
FIG. 4—The nucleotide (SEQ.ID.NO.:8) and amino acid sequence (SEQ.ID.NO.:9) of the protease T catalytic domain in the zymogen activation construct is shown.
FIG. 5—Polyacrylamide gel and Western blot analyses of the recombinant protease PFEK-proteaseT-6XHIS. Shown is the polyacrylamide gel containing samples of the novel serine protease PFEK-proteaseT-6XHIS stained with Coomassie Brilliant Blue (Leftmost 1, 2). The relative molecular masses are indicated by the positions of protein standards (M). In the indicated lanes, the purified zymogen was either untreated (−) or digested with EK (+) which was used to cleave and activate the zymogen into its active form. Western blot of the gel, probed with the anti-FLAG MoAb M2, is also shown (Rightmost 1, 2). This demonstrates the quantitative cleavage of the expressed and purified zymogen to generate the processed and activated protease. Since the FLAG epitope is located just upstream of the of the EK pro sequence, cleavage with EK generates a FLAG-containing polypeptide which is too small to be retained in the polyacrylamide gel, and is therefore not detected in the +EK lane.
FIG. 6—Functional amidolytic activities of the recombinant protease T-6XHIS expressed, purified and activated from the activation construct were determined using chromogenic substrates.
Table 1—The specific activity (nmole pNA produced/min/ug protein) of recombinant activated protease T-6XHIS, determined for the various substrates analyzed, is shown.
The term “protein domain” as used herein refers to a region of a protein that can fold into a stable three-dimensional structure independent to the rest of the protein. This structure may maintain a specific function associated with the domain's function within the protein including enzymatic activity, creation of a recognition motif for another molecule, or provide necessary structural components for a protein to exist in a particular environment. Protein domains are usually evolutionarily conserved regions of proteins, both within a protein superfamily and within other protein superfamilies that perform similar functions.
The term “protein superfamily” as used herein refers to proteins whose evolutionary relationship may not be entirely established or may be distant by accepted phylogenetic standards, but show similar three dimensional structure or display unique consensus of critical amino acids. The term “protein family” as used herein refers to proteins whose evolutionary relationship has been established by accepted phylogenic standards.
The term “fusion protein” as used herein refers to protein constructs that are the result of combining multiple protein domains or linker regions for the purpose of gaining function of the combined functions of the domains or linker regions. This is most often accomplished by molecular cloning of the nucleotide sequences to result in the creation of a new polynucleotide sequence that codes for the desired protein. Alternatively, creation of a fusion protein may be accomplished by chemically joining two proteins together.
The term “linker region” or “linker domain” or similar such descriptive terms as used herein refers to stretches of polynucleotide or polypeptide sequence that are used in the construction of a cloning vector or fusion protein. Functions of a linker region can include introduction of cloning sites into the nucleotide sequence, introduction of a flexible component or space-creating region between two protein domains, or creation of an affinity tag for specific molecule interaction. A linker region may be introduced into a fusion protein without a specific purpose, but results from choices made during cloning.
The term “pre-sequence” as used herein refers to a nucleotide sequence that encodes a secretion signal amino acid sequence. A wide variety of such secretion signal sequences are known to those skilled in the art, and are suitable for use in the present invention. Examples of suitable pre-sequences include, but are not limited to, prolactinFLAG, trypsinogen, and chymoFLAG.
The term “pro-sequence” as used herein refers to a nucleotide sequence that encodes a cleavage site for a restriction protease. A wide variety of cleavage sites for restriction proteases are known to those skilled in the art, and are suitable for use in the present invention. Examples of suitable pro-sequences include, but are not limited to, EK, FXa, and thrombin.
The term “cloning site” or “polycloning site” as used herein refers to a region of the nucleotide sequence contained within a cloning vector or engineered within a fusion protein that has one or more available restriction endonuclease consensus sequences. The use of a correctly chosen restriction endonuclease results in the ability to isolate a desired nucleotide sequence that codes for an in-frame sequence relative to a start codon that yields a desirable protein product after transcription and translation. These nucleotide sequences can then be introduced into other cloning vectors, used create novel fusion proteins, or used to introduce specific site-directed mutations. It is well known by those in the art that cloning sites can be engineered at a desired location by silent mutations, conserved mutation, or introduction of a linker region that contains desired restriction enzyme consensus sequences. It is also well known by those in the art that the precise location of a cloning site can be flexible so long as the desired function of the protein or fragment thereof being cloned is maintained.
The term “tag” as used herein refers to a nucleotide sequence that encodes an amino acid sequence that facilitates isolation, purification or detection of a fusion protein containing the tag. A wide variety of such tags are known to those skilled in the art, and are suitable for use in the present invention. Suitable tags include, but are not limited to, HA-tag, His-tag, biotin, avidin, and antibody binding sites.
As used herein, “expression vectors” are defined herein as DNA sequences that are required for the transcription of cloned copies of genes and the translation of their mRNAs in an appropriate host. Such vectors can be used to express eukaryotic genes in a variety of hosts such as bacteria including E. coli, blue-green algae, plant cells, insect cells, fungal cells including yeast cells, and animal cells.
The term “catalytic domain cassette” as used herein refers to a nucleotide sequence that encodes an amino acid sequence encoding at least the catalytic domain of the serine protease of interest. A wide variety of protease catalytic domains may be inserted into the expression vectors of the present invention, including those presently known to those skilled in the art, as well as those not yet having an isolated nucleotide sequence encodes it, once the nucleotide sequence is isolated.
As used herein, a “functional derivative” of the nucleotide sequence, vector, or polypeptide possesses a biological activity (either functional or structural) that is substantially similar to the properties described herein. The term “functional derivatives” is intended to include the “fragments,” “variants,” “degenerate variants,” “analogs” and “homologues” of the nucleotide sequence, vector, or polypeptide. The term “fragment” is meant to refer to any nucleotide sequence, vector, or polypeptide subset of the modules described as pre and pro sequences used for the activation of expressed zymogen precursors. The term “variant” is meant to refer to a nucleotide or amino acid sequence that is substantially similar in structure and function to either the entire nucleic acid sequence or encoded protein or to a fragment thereof. A nucleic acid or amino acid sequence is “substantially similar” to another if both molecules have similar structural characteristics or if both molecules possess similar biological properties. Therefore, if the two molecules possess substantially similar activity, they are considered to be variants even if the structure of one of the molecules is not found in the other or even if the two amino acid sequences are not identical. The term “analog” refers to a protein molecule that is substantially similar in function to another related protein.
Herein we describe a novel serine protease, molecularly cloned from esophageal tissue, termed protease T. FastA searches of the Genbank database indicate that protease T has the highest similarity to a previously characterized partial serine protease cDNA cloned from rat hippocampus called BSP2 (Davies, et al. (1998). J Biol Chem 273:23004-11)[48.2% identity in 284 amino acid overlap]. Other published human serine proteases are prostasin (Yu et al. (1996). Genomics 32:334-40) [43.8% identity in 281 amino acid overlap] and tryptase (Miller et al. (1990). J. Clin. Invest. 86:864-700) [43.8% identity in 274 amino acid overlap]. Additional homology searches of the Genbank database with the protease T nucleotide sequence revealed homology with non-contiguous regions of the human cosmid clone (400D1, Genbank accession #AC004036), which maps to chromosome 16p13.3. Assembly of a continuous nucleic acid sequence from the proposed intron/exon junctions described in the Genbank accession #AC004036 annotation produces a nucleic acid sequence that is shorter and also non-contiguous, and thus substantially different from, protease T of the present invention. Thus, it is likely that the exons delineated in the Genbank accession #AC004036 annotation is incorrect. Therefore, protease T of the present invention represents a previously undescribed protease. The use of the previously undescribed sequence of the present invention indicates that chromosome 16p13.3 is the correct the position of the protease T gene. We have detected the protease T mRNA in stomach and testis and leukocytes and the Jurkat (ATCC TIB-152) T cell line. In addition the mRNA for this serine protease was found in spinal cord and many subregions of the brain. Therefore protease T, or manipulation of this enzyme by chemical modulators, may be useful for treatment of male infertility, immune function or certain neurological disorders. Because protease T is derived from a human host, it is less likely to induce an immunogenic or allergic reaction in sensitive individuals, and therefore protease T may also be useful for formulation of compositions for cleansing agents, food processing, fabric processing, laundry detergents and skin care products.
The present invention relates to DNA encoding the serine protease T that was identified from a cDNA library, constructed using poly A RNA isolated from esophageal tissue. The protease T as used herein, refers to the encoded protein product which can specifically function as a protease.
The complete amino acid sequence of protease T was not previously known, nor was the complete nucleotide sequence encoding protease T known. This is the first reported cloning of a full length DNA molecule encoding protease T. Based on mRNA distribution, it is predicted that a restricted number of tissues and cell types will contain the described protease. Human cell lines capable of producing protease T include, but are not limited to fibroblasts and Jurkat. Other tissue types may be human retina leukocytes, stomach, testis, spinal cord and many subregions of the brain.
Other cells and cell lines may also be suitable for use to isolate the protease T cDNA. Selection of suitable cells may be done by screening for protease T proteolytic activity in conditioned cell media. Cell types that possess protease T proteolytic activity in this assay may be suitable for the isolation of the protease T DNA or mRNA.
Any of a variety of procedures known in the art may be used to molecularly clone the protease T DNA. These methods include, but are not limited to, direct functional expression of protease genes following the construction of a protease T-containing cDNA library in an appropriate expression vector system. Another method is to screen protease T-containing cDNA library constructed in a bacteriophage or plasmid shuttle vector with a labeled oligonucleotide probe designed from the amino acid sequence of the protease T DNA. An additional method consists of screening a protease T-containing cDNA library constructed in a bacteriophage or plasmid shuttle vector with a partial cDNA encoding the protease T protein. This partial cDNA is obtained by the specific polymerase chain reaction (PCR) amplification of protease T DNA fragments through the design of degenerate oligonucleotide primers from the amino acid sequence of the purified protease T protein. Expressed sequence tags (EST)s, identified through homology searching of nucleic acid databases (Altschul et al. (1990). J. Mol. Biol. 215:403-10; Pearson and Lipman (1988). Proc. Natl. Acad. Sci. U.S.A. 85:2444-8), are also available for this purpose. This particular protease is a member of a multigene family containing highly conserved residues and motifs. Thus, cDNA library screening under reduced stringency to identify related but non-identical homologous cDNAs is possible. More recently, direct PCR using degenerate oligonucleotides of cDNA reverse transcribed from RNA of a given cell type, has been a fruitful approach to isolate novel related cDNAs of interest. Alternatively, the full-length cDNA sequence once published, may be obtained by the specific PCR amplification, through the design of matching oligonucleotide primers flanking the entire coding sequence.
Another method is to isolate RNA from protease T-producing cells and translate the RNA into protein via an in vitro or an in vivo translation system. The translation of the RNA into a protein will result in the production of at least a portion of the protease T protein that can be identified by, for example, immunological reactivity with an anti-protease T antibody. Should the entire catalytic domain be translated, functional proteolytic activity of the protease T protein could be used to identify RNA fractions containing the protease T mRNA. In this method, pools of RNA isolated from protease T-producing cells can be analyzed for the presence of an RNA that encodes at least a portion of the protease T protein. Further fractionation of the RNA pool can be done to purify the protease T RNA from non-protease T RNA. The peptide or protein produced by this method may be analyzed to provide amino acid sequences, which in turn may be used to provide primers for production of protease T cDNA. Similarly, RNA used for translation can be analyzed to provide nucleotide sequences and may be used to produce probes for the production of the protease T cDNA. This method is known in the art and can be found in, for example, (Maniatis et al. (1989). 1-1626).
It is readily apparent to those skilled in the art that other types of libraries, as well as libraries constructed from other cells or cell types, may be useful for isolating protease T-encoding DNA. Other types of libraries include, but are not limited to, cDNA libraries derived from other cells, from non-human organisms, and genomic DNA libraries that include YAC (yeast artificial chromosome) and cosmid libraries.
It is readily apparent to those skilled in the art that suitable cDNA libraries may be prepared from cells or cell lines which have protease T proteolytic activity. The selection of cells or cell lines for use in preparing a cDNA library to isolate the protease T cDNA may be done by first measuring cell associated protease T proteolytic activity using the measurement of protease T-associated biological activity or a protease T specific immunological reactivity.
Preparation of cDNA libraries can be performed by standard techniques well known in the art. Well known cDNA library construction techniques can be found for example, in (Maniatis et al. (1989). 1-1626).
It is also readily apparent to those skilled in the art that DNA encoding protease T may also be isolated from a suitable genomic DNA library. Construction of genomic DNA libraries can be performed by standard techniques well known in the art. Well known genomic DNA library construction techniques can be found in (Maniatis et al. (1989). 1-1626).
In order to clone the protease T gene by the above methods, the amino acid sequence of protease T may be necessary. To accomplish this, the protease T protein may be purified and partial amino acid sequence determined by automated sequencers. It is not necessary to determine the entire amino acid sequence, but the linear sequence of two regions of 6 to 8 amino acids from the protein is determined for the production of primers for PCR amplification of a partial protease T DNA fragment. Alternatively, a longer degenerate oligonucleotide probe can be synthesized with a larger consecutive stretch of amino acid sequence determined. This oligonucleotide probe can be labeled and used to screen a suitable cDNA or genomic library, under the appropriate stringency, to isolate DNA corresponding to protease T
Once suitable amino acid sequences have been identified, the DNA sequences capable of encoding them are synthesized. Because the genetic code is degenerate, more than one codon may be used to encode a particular amino acid, and therefore, the amino acid sequence can be encoded by any of a set of similar DNA oligonucleotides. Only one member of the set will be identical to the protease T sequence, but will be capable of hybridizing to protease T DNA even in the presence of DNA oligonucleotides with mismatches. The mismatched DNA oligonucleotides may still sufficiently hybridize to the protease T DNA to permit identification and isolation of protease T encoding DNA. DNA isolated by these methods can be used to screen DNA libraries from a variety of cell types, from invertebrate and vertebrate sources, and to isolate homologous genes.
Purified biologically active protease T may have several different physical forms. Protease T may exist as a full-length nascent or unprocessed polypeptide, or as partially processed polypeptides or combinations of processed polypeptides. The full-length nascent protease T polypeptide may be posttranslationally modified by specific proteolytic cleavage events, which result in the formation of fragments of the full-length nascent polypeptide. A fragment, or physical association of fragments may have the full biological activity associated with protease T however, the degree of protease T activity may vary between individual protease T fragments and physically associated protease T polypeptide fragments.
The cloned protease T DNA obtained through the methods described herein may be recombinantly expressed by molecular cloning into an expression vector containing a suitable promoter and other appropriate transcription regulatory elements, and transferred into prokaryotic or eukaryotic host cells to produce recombinant protease T protein. Techniques for such manipulations are fully described (Maniatis et al. (1989). 1-1626), and are well known in the art.
Expression vectors are defined herein as DNA sequences that are required for the transcription of cloned copies of genes and the translation of their mRNAs in an appropriate host. Such vectors can be used to express eukaryotic genes in a variety of hosts such as bacteria including E. coli, blue-green algae, plant cells, insect cells, fungal cells including yeast cells, and animal cells.
Specifically designed vectors allow the shuttling of DNA between hosts such as bacteria-yeast or bacteria-animal cells or bacteria-fungal cells or bacteria-invertebrate cells. An appropriately constructed expression vector should contain: an origin of replication for autonomous replication in host cells, selectable markers, a limited number of useful restriction enzyme sites, a potential for high copy number, and active promoters. A promoter is defined as a DNA sequence that directs RNA polymerase to bind to DNA and initiate RNA synthesis. A strong promoter is one that causes mRNAs to be initiated at high frequency. Expression vectors may include, but are not limited to, cloning vectors, modified cloning vectors, specifically designed plasmids or viruses.
A variety of mammalian expression vectors may be used to express recombinant protease T in mammalian cells. Commercially available mammalian expression vectors which may be suitable for recombinant protein expression, include but are not limited to, pCI Neo (Promega, Madison, Wis., Madison Wis.), pMAMneo (Clontech, Palo Alto, Calif.), pcDNA3 (InVitrogen, San Diego, Calif.), pMC1neo (Stratagene, La Jolla, Calif.), pXT1 (Stratagene, La Jolla, Calif.), pSG5 (Stratagene, La Jolla, Calif.), EBO-pSV2-neo (ATCC 37593) pBPV-1 (8-2) (ATCC 37110), pdBPV-MMTneo (342-12) (ATCC 37224), pRSVgpt (ATCC 37199), pRSVneo (ATCC 37198), pSV2-dhfr (ATCC 37146), pUCTag (ATCC 37460), and 1ZD35 (ATCC 37565).
A variety of bacterial expression vectors may be used to express recombinant protease T in bacterial cells. Commercially available bacterial expression vectors which may be suitable for recombinant protein expression include, but are not limited to pET vectors (Novagen, Inc., Madison Wis.) and pQE vectors (Qiagen, Valencia, Calif.) pGEX (Pharmacia Biotech Inc., Piscataway, N.J.).
A variety of fungal cell expression vectors may be used to express recombinant protease T in fungal cells such as yeast. Commercially available fungal cell expression vectors which may be suitable for recombinant protease T expression include but are not limited to pYES2 (InVitrogen, San Diego, Calif.) and Pichia expression vector (InVitrogen, San Diego, Calif.).
A variety of insect cell expression systems may be used to express recombinant protease T in insect cells. Commercially available baculovirus transfer vectors which may be suitable for the generation of a recombinant baculovirus for recombinant protein expression in Sf9 cells include but are not limited to pFastBac1 (Life Technologies, Gaithersberg, Md.) pAcSG2 (Pharmingen, San Diego, Calif.) pBlueBacII (InVitrogen, San Diego, Calif.). In addition, a class of insect cell vectors that permit the expression of recombinant proteins in Drosophila Schneider line 2 (S2) cells is also available (InVitrogen, San Diego, Calif.).
DNA encoding the protease T may be subcloned into an expression vector for expression in a recombinant host cell. Recombinant host cells may be prokaryotic or eukaryotic, including but not limited to bacteria such as E. coli, fungal cells such as yeast, mammalian cells including but not limited to cell lines of human, bovine, porcine, monkey and rodent origin, and insect cells including but not limited to Drosophila S2 (ATCC CRL-1963) and silkworm Sf9 (ATCC CRL-1711), derived cell lines. Cell lines derived from mammalian species which may be suitable and which are commercially available, include but are not limited to, CV-1 (ATCC CCL 70), COS-1 (ATCC CRL 1650), COS-7 (ATCC CRL 1651), CHO-K1 (ATCC CCL 61), 3T3 (ATCC CCL 92), NIH/3T3 (ATCC CRL 1658), HeLa (ATCC CCL 2), C127I (ATCC CRL 1616), BS-C-1 (ATCC CCL 26), MRC-5 (ATCC CCL 171), L-cells, and HEK-293 (ATCC CRL 1573).
The expression vector may be introduced into host cells via any one of a number of techniques including but not limited to transformation, transfection, protoplast fusion, lipofection, and electroporation. The expression vector-containing cells are clonally propagated and individually analyzed to determine whether they produce protease T protein. Identification of protease ESO expressing host cell clones may be done by several means, including but not limited to immunological reactivity with anti-protease T antibodies, and the presence of host cell-associated protease T proteolytic activity.
Expression of protease T DNA may also be performed using in vitro produced synthetic mRNA. Synthetic mRNA or mRNA isolated from protease T producing cells can be efficiently translated in various cell-free systems, including but not limited to wheat germ extracts and reticulocyte extracts, as well as efficiently translated in cell based systems, including but not limited to microinjection into frog oocytes, with microinjection into frog oocytes being generally preferred.
To determine the protease T DNA sequence(s) that yields optimal levels of protease T proteolytic activity and/or protease T protein, protease T DNA molecules including, but not limited to, the following can be constructed: the full-length open reading frame of the protease T cDNA encoding the 30-kDa protein from approximately base 36 to approximately base 905 (these numbers correspond to first nucleotide of first methionine and last nucleotide before the first stop codon;
Host cell transfectants and microinjected oocytes may be used to assay both the levels of protease T proteolytic activity and levels of protease T protein by the following methods. In the case of recombinant host cells, this involves the co-transfection of one or possibly two or more plasmids, containing the protease T DNA encoding one or more fragments or subunits. In the case of oocytes, this involves the co-injection of synthetic RNAs encoding protease T. Following an appropriate period of time to allow for expression, cellular protein is metabolically labeled with, for example. 35S-methionine for 24 hours, after which cell lysates and cell culture supernatants are harvested and subjected to immunoprecipitation with polyclonal antibodies directed against the protease T protein.
Other methods for detecting protease T expression involve the direct measurement of protease T proteolytic activity in whole cells transfected with protease T cDNA or oocytes injected with protease T mRNA. Proteolytic activity can be measured by analyzing conditioned media or cell lysates by hydrolysis of a chromogenic or fluorogenic substrate. In the case of recombinant host cells expressing protease T, higher levels of substrate hydrolysis would be observed relative to mock transfected cells or cells transfected with expression vector lacking the protease T DNA insert. In the case of oocytes, lysates or conditioned media from those injected with RNA encoding protease T, would show higher levels of substrate hydrolysis than those oocytes programmed with an irrelevant RNA.
Other methods for detecting proteolytic activity include, but are not limited to, measuring the products of proteolytic degradation of radiolabeled proteins (Coolican et al. (1986). J. Biol. Chem. 261:4170-6), fluorometric (Lonergan et al. (1995). J. Food Sci. 60:72-3, 78; Twining (1984). Anal. Biochem. 143:30-4) or colorimetric (Buroker-Kilgore and Wang (1993). Anal. Biochem. 208:387-92) analyses of degraded protein substrates. Zymography following SDS polyacrylamide gel electrophoresis (Wadstroem and Smyth (1973). Sci. Tools 20:17-21), as well as by fluorescent resonance energy transfer (FRET)-based methods (Ng and Auld (1989). Anal. Biochem. 183:50-6) are also methods used to detect proteolytic activity.
Levels of protease T protein in host cells can be quantified by immunoaffinity protease T-specific affinity beads or protease T-specific antibodies are used to isolate for example. 35S-methionine labeled or unlabelled protease T protein. Labeled protease T protein is analyzed by SDS-PAGE. Unlabelled protease T protein is detected by Western blotting, ELISA or RIA assays employing protease T specific antibodies.
Because the genetic code is degenerate, more than one codon may be used to encode a particular amino acid, and therefore, the amino acid sequence can be encoded by any of a set of similar DNA oligonucleotides. Only one member of the set will be identical to the protease T sequence but will be capable of hybridizing to protease T DNA even in the presence of DNA oligonucleotides with mismatches under appropriate conditions. Under alternate conditions, the mismatched DNA oligonucleotides may still hybridize to the protease T DNA to permit identification and isolation of protease T encoding DNA.
DNA encoding protease T from a particular organism may be used to isolate and purify homologues of the protease T DNA from other organisms. To accomplish this, the first protease T DNA may be mixed with a sample containing DNA encoding homologues of protease T under appropriate hybridization conditions. The hybridized DNA complex may be isolated and the DNA encoding the homologous DNA may be purified therefrom.
It is known that there is a substantial amount of redundancy in the various codons that code for specific amino acids. Therefore, this invention is also directed to those DNA sequences that contain alternative codons that code for the eventual translation of the identical amino acid. For purposes of this specification, a sequence bearing one or more replaced codons will be defined as a degenerate variation. Also included within the scope of this invention are mutations either in the DNA sequence or the translated protein which do not substantially alter the ultimate physical properties of the expressed protein. For example, substitution of valine for leucine, arginine for lysine, or asparagine for glutamine may not cause a change in functionality of the polypeptide.
It is known that DNA sequences coding for a peptide may be altered so as to code for a peptide having properties that are different than those of the naturally occurring peptide. Methods of altering the DNA sequences include, but are not limited to site directed mutagenesis. Examples of altered properties include but are not limited to changes in the affinity of an enzyme for a substrate or a receptor for a ligand.
Several recombinant serine protease purification procedures are available and suitable for use (Hansson et al. (1994). J. Biol. Chem. 269:19420-6; Little et al. (1997). J. Biol. Chem. 272:25135-25142; Takayama et al. (1997). J. Biol. Chem. 272:21582-21588; Yamaoka et al. (1998). J. Biol. Chem. 273:11895-11901). As described above for purification of protease T from natural sources, recombinant protease T may be purified from cell lysates and extracts, or from conditioned culture medium, by various combinations of, or individual application of salt fractionation, ion exchange chromatography, size exclusion chromatography, hydroxylapatite adsorption chromatography and hydrophobic interaction chromatography. Following expression of protease T in a recombinant host cell, as is the case for many members of the S1 serine protease family, protease T protein may be recovered as an inactive zymogen precursor form which may require a limited proteolysis to become the proteolytically active.
A major drawback in the expression of full-length serine protease cDNAs for biochemical and enzymological analyses is the overwhelming potential for the production of large amounts of the inactive zymogen. These zymogen precursors often have little or no significant proteolytic activity and thus must be activated by either one of two methods currently available. One method relies on the autoactivation (Little et al. (1997). J. Biol. Chem. 272:25135-25142), which may occur in homogeneous purified protease preparations under the correct set of circumstances. Investigators must rigorously evaluate these conditions, which often require high protein concentrations. The second method is the use of a surrogate activating protease, such as trypsin, to cleave the serine protease under investigation, and either inactivate (Takayama et al. (1997). J. Biol. Chem. 272:21582-21588) or physically remove (Hansson et al. (1994). J. Biol. Chem. 269:19420-6) the contaminating protease following activation. In both methods however, the exact conditions must be established empirically and activating reactions monitored carefully, since inadequate activation or over-digestion leading to degradation and sample loss could always be possible consequences of these activating techniques. Investigators studying particular members of the S1 serine protease family have exploited the use of restriction proteinases on the activation of expressed zymogens in bacteria (Wang et al. (1995). Biol. Chem. Hoppe-Seyler 376:681-4) and mammalian cells (Yamashiro et al. (1997). Biochim. Biophys. Acta 1350:11-14). In one report, the authors successfully engineered the secretion of proteolytically processed and activated murine granzyme B by taking advantage of the endogenous yeast KEX2 signal peptidase in a Pichia pastoris expression system (Pham et al. (1998). J. Biol. Chem. 273:1629-1633). Another aspect of the present invention provides a fusion gene comprising protease T that encodes a protease T that facilitates activation of the protease.
DNA clones, including protease T DNA, are identified which encode proteins that, when expressed in a recombinant host, produce protein with the amino acid sequence of protease T, which may or may not possess a proteolytic activity. The expression of protease T DNA results in the reconstitution of the properties observed in oocytes injected with protease T-encoding poly (A)+ RNA.
Recombinant protease T can be separated from other cellular proteins by use of an immunoaffinity column made with monoclonal or polyclonal antibodies specific for full-length nascent protease T polypeptide fragments of protease T. Monospecific antibodies to protease T are purified from mammalian antisera containing antibodies reactive against protease T or are prepared as monoclonal antibodies reactive with protease T using the technique of (Kohler and Milstein (1976). Eur J Immunol 6:511-9). Monospecific antibody as used herein is defined as a single antibody species or multiple antibody species with homogenous binding characteristics for protease T. Homogenous binding as used herein refers to the ability of the antibody species to bind to a specific antigen or epitope, such as those associated with the protease T, as described above. Protease T specific antibodies are raised by immunizing animals such as mice, rats, guinea pigs, rabbits, goats, horses and the like, with rabbits being preferred, with an appropriate concentration of protease T either with or without an immune adjuvant.
Preimmune serum is collected prior to the first immunization. Each animal receives between about 0.1 mg and about 1000 mg of protease T protein or peptide(s), derived from the deduced protease T DNA sequence or perhaps by the chemical degradation or enzymatic digestion of the protease T protein itself, associated with an acceptable immune adjuvant. Such acceptable adjuvants include, but are not limited to, Freund's complete, Freund's incomplete, alum-precipitate, water in oil emulsion containing Corynebacterium parvum and tRNA, or Titermax (CytRx, Norcross, Ga.). The initial immunization consists of protease T antigen in, preferably, Freund's complete adjuvant at multiple sites either subcutaneously (SC), intraperitoneally (IP) or both. Each animal is bled at regular intervals, preferably weekly, to determine antibody titer. The animals may or may not receive booster injections following the initial immunization. Those animals receiving booster injections are generally given an equal amount of the antigen in Freund's incomplete adjuvant by the same route. Booster injections are given at about three-weck intervals until maximal titers are obtained. At about 7 days after each booster immunization or about weekly after a single immunization, the animals are bled, the serum collected, and aliquots are stored at about −20° C.
Monoclonal antibodies (MoAb) reactive with protease T are prepared by immunizing inbred mice, preferably Balb/c, with protease T protein or peptide(s), derived from the deduced protease T DNA sequence or perhaps by the chemical degradation or enzymatic digestion of the protease T protein itself. The mice are immunized by the IP or SC route with about 0.1 mg to about 10 mg, preferably about 1 mg, of protease T antigen in about 0.5 ml buffer or saline incorporated in an equal volume of an acceptable adjuvant, as discussed above. Freund's complete adjuvant is preferred. The mice receive an initial immunization on day 0 and are rested for about 3 to about 30 weeks. Immunized mice are given one or more booster immunizations of about 0.1 to about 10 mg of protease T antigen in a buffer solution such as phosphate buffered saline by the intravenous (IV) route. Lymphocytes, from antibody positive mice, preferably splenic lymphocytes, are obtained by removing spleens from immunized mice by standard procedures known in the art. Hybridoma cells are produced by mixing the splenic lymphocytes with an appropriate fusion partner, preferably myeloma cells, under conditions that will allow the formation of stable hybridomas. Fusion partners may include, but are not limited to: mouse myelomas P3/NS1/Ag 4-1; MPC-11; S-194 and Sp 2/0, with Sp 2/0 being generally preferred. The antibody producing cells and myeloma cells are fused in polyethylene glycol, about 1000 mol. wt., at concentrations from about 30% to about 50%. Fused hybridoma cells are selected by growth in hypoxanthine, thymidine and aminopterin supplemented Dulbecco's Modified Eagles Medium (DMEM) by procedures known in the art. Supernatant fluids are collected from growth positive wells on about days 14, 18, and 21 and are screened for antibody production by an immunoassay such as solid phase immunoradioassay (SPIRA) using protease T or antigenic peptide(s) as the antigen. The culture fluids are also tested in the Ouchterlony precipitation assay to determine the isotype of the MoAb. Hybridoma cells from antibody positive wells are cloned by a technique such as the soft agar technique of MacPherson, Soft Agar Techniques, in Tissue Culture Methods and Applications, Knise and Paterson, Eds., Academic Press, 1973.
Monoclonal antibodies are produced in vivo by injection of pristane primed Balb/c mice, approximately 0.5 ml per mouse, with about 2×106 to about 6×106 hybridoma cells about 4 days after priming. Ascites fluid is collected at approximately 8-12 days after cell transfer and the monoclonal antibodies are purified by techniques known in the art.
In vitro production of anti-protease T MoAb is carried out by growing the hybridoma in DMEM containing about 2% fetal calf serum to obtain sufficient quantities of the specific MoAb. The monoclonal antibodies are purified by techniques known in the art.
Antibody titers of ascites or hybridoma culture fluids are determined by various serological or immunological assays which include, but are not limited to, precipitation, passive agglutination, enzyme-linked immunosorbent antibody (ELISA) technique and radioimmunoassay (RIA) techniques. Similar assays are used to detect the presence of protease T in body fluids or tissue and cell extracts.
It is readily apparent to those skilled in the art that the above described methods for producing monospecific antibodies may be utilized to produce antibodies specific for protease T polypeptide fragments, or full-length nascent protease T polypeptide. Specifically, it is readily apparent to those skilled in the art that monospecific antibodies may be generated which are specific for only one or more protease T epitopes.
Protease T antibody affinity columns are made by adding the antibodies to Affigel-10 (Bio-Rad), a gel support which is activated with N-hydroxysuccinimide esters such that the antibodies form covalent linkages with the agarose gel bead support. The antibodies are then coupled to the gel via amide bonds with the spacer arm. The remaining activated esters are then quenched with 1M ethanolamine HCl (pH 8). The column is washed with water followed by 0.23 M glycine HCl (pH 2.6) to remove any non-conjugated antibody or extraneous protein. The column is then equilibrated in phosphate buffered saline (pH 7.3) and the cell culture supernatants or cell extracts containing protease T are slowly passed through the column. The column is then washed with phosphate buffered saline until the optical density (A280) falls to background, then the protein is eluted with 0.23 M glycine-HCl (pH 2.6). The purified protease T protein is then dialyzed against phosphate buffered saline.
Protease T mRNA is expressed in stomach, testis, retina, and in fibroblasts, where the encoded protease T protein may perform important functions during normal physiology, and possibly pathological states. In addition protease T mRNA is detected in many neurological tissues such as spinal cord, and several regions of the brain. Protease T mRNA is also found in leukocytes and in the Jurkat (ATCC TIB-152) T cell line and consequently may be expressed in T cells. Thus, modulators of protease T function could be used to treat disorders effecting these tissues. Modulators of protease T function could therefore potentially be used to treat gastric, testicular, retinal, dermatological, neurological/neurodegenerative or immunological disorders.
The present invention is also directed to methods for screening for compounds that modulate the expression of DNA or RNA encoding protease T as well as the function of protease T protein in vivo. Compounds that modulate these activities may be DNA, RNA, peptides, proteins, or non-proteinaceous organic molecules. Compounds may modulate by increasing or attenuating the expression of DNA or RNA encoding protease T, or the function of protease T protein. Compounds that modulate the expression of DNA or RNA encoding protease T or the function of protease T protein may be detected by a variety of assays. The assay may be a simple “yes/no” assay to determine whether there is a change in expression or function. The assay may be made quantitative by comparing the expression or function of a test sample with the levels of expression or function in a standard sample. Modulators identified in this process are potentially useful as therapeutic agents. Methods for detecting compounds that modulate protease T proteolytic activity comprise combining compound, protease T and a suitable labeled substrate and monitoring an effect of the compound on the protease by changes in the amount of substrate as a function of time. Labeled substrates include, but are not limited to, substrates that are radiolabeled (Coolican et al. (1986). J. Biol. Chem. 261:4170-6), fluorometric (Lonergan et al. (1 995). J. Food Sci. 60:72-3, 78; Twining (1984). Anal. Biochem. 143:30-4) or colorimetric (Buroker-Kilgore and Wang (1993). Anal. Biochem. 208:387-92). Zymography following SDS polyacrylamide gel electrophoresis (Wadstroem and Smyth (1973). Sci. Tools 20:17-21), as well as by fluorescent resonance energy transfer (FRET)-based methods (Ng and Auld (1989). Anal. Biochem. 183:50-6) are also methods used to detect compounds that modulate protease T proteolytic activity. Compounds that are agonists will increase the rate of substrate degradation and will result in less remaining substrate as a function of time. Compounds that are antagonists will decrease the rate of substrate degradation and will result in greater remaining substrate as a function of time.
Kits containing protease T DNA or RNA, antibodies to protease T, or protease T protein may be prepared. Such kits are used to detect DNA that hybridizes to protease T DNA or to detect the presence of protease T protein or peptide fragments in a sample. Such characterization is useful for a variety of purposes including but not limited to forensic analyses, diagnostic applications, and epidemiological studies.
The DNA molecules, RNA molecules, recombinant protein and antibodies of the present invention may be used to screen and measure levels of protease T DNA, protease T RNA or protease T protein. The recombinant proteins, DNA molecules, RNA molecules and antibodies lend themselves to the formulation of kits suitable for the detection and typing of protease T. Such a kit would comprise a compartmentalized carrier suitable to hold in close confinement at least one container. The carrier would further comprise reagents such as recombinant protease T protein or anti-protease T antibodies suitable for detecting protease T protein. The carrier may also contain a means for detection such as labeled antigen or enzyme substrates or the like.
Nucleotide sequences that are complementary to the protease T encoding DNA sequence can be synthesized for antisense therapy. These antisense molecules may be DNA, stable derivatives of DNA such as phosphorothioates or methylphosphonates, RNA, stable derivatives of RNA such as 2′-O-alkylRNA, or other protease T antisense oligonucleotide mimetics. protease T anti sense molecules may be introduced into cells by microinjection, liposome encapsulation or by expression from vectors harboring the antisense sequence. protease T antisense therapy may be particularly useful for the treatment of diseases where it is beneficial to reduce protease T expression or activity.
Protease T gene therapy may be used to introduce protease T into the cells of target organisms. The protease T gene can be ligated into viral vectors that mediate transfer of the protease T DNA by infection of recipient host cells. Suitable viral vectors include retrovirus, adenovirus, adeno-associated virus, herpes virus, vaccinia virus, poliovirus and the like. Alternatively, protease T DNA can be transferred into cells for gene therapy by non-viral techniques including receptor-mediated targeted DNA transfer using ligand-DNA conjugates or adenovirus-ligand-DNA conjugates, lipofection membrane fusion or direct microinjection. These procedures and variations thereof are suitable for ex vivo as well as in vivo protease T gene therapy. Protease T gene therapy may be particularly useful for the treatment of diseases where it is beneficial to elevate protease T expression or activity.
Pharmaceutically useful compositions comprising protease T DNA, protease T RNA, or protease T protein, or modulators of protease T activity, may be formulated according to known methods such as by the admixture of a pharmaceutically acceptable carrier. Examples of such carriers and methods of formulation may be found in Remington's Pharmaceutical Sciences. To form a pharmaceutically acceptable composition suitable for effective administration, such compositions will contain an effective amount of the protein, DNA, RNA, or modulator.
Therapeutic or diagnostic compositions of the invention are administered to an individual in amounts sufficient to treat or diagnose disorders in which modulation of protease T-related activity is indicated. The effective amount may vary according to a variety of factors such as the individual's condition, weight, sex and age. Other factors include the mode of administration. The pharmaceutical compositions may be provided to the individual by a variety of routes such as subcutaneous, topical, oral and intramuscular.
The term “chemical derivative” describes a molecule that contains additional chemical moieties that are not normally a part of the base molecule. Such moieties may improve the solubility, half-life, absorption, etc. of the base molecule. Alternatively the moieties may attenuate undesirable side effects of the base molecule or decrease the toxicity of the base molecule. Examples of such moieties are described in a variety of texts, such as Remington's Pharmaceutical Sciences.
Compounds identified according to the methods disclosed herein may be used alone at appropriate dosages defined by routine testing in order to obtain optimal inhibition of the protease T activity while minimizing any potential toxicity. In addition, co-administration or sequential administration of other agents may be desirable.
The present invention also has the objective of providing suitable topical, oral, systemic and parenteral pharmaceutical formulations for use in the novel methods of treatment of the present invention. The compositions containing compounds or modulators identified according to this invention as the active ingredient for use in the modulation of protease T activity can be administered in a wide variety of therapeutic dosage forms in conventional vehicles for administration. For example, the compounds or modulators can be administered in such oral dosage forms as tablets, capsules (each including timed release and sustained release formulations), pills, powders, granules, elixirs, tinctures, solutions, suspensions, syrups and emulsions, or by injection. Likewise, they may also be administered in intravenous (both bolus and infusion), intraperitoneal, subcutaneous, topical with or without occlusion, or intramuscular form, all using forms well known to those of ordinary skill in the pharmaceutical arts. An effective but non-toxic amount of the compound desired can be employed as a protease T modulating agent.
The daily dosage of the products may be varied over a wide range from 0.01 to 1,000 mg per patient, per day. For oral administration, the compositions are preferably provided in the form of scored or unscored tablets containing 0.01, 0.05, 0.1, 0.5, 1.0, 2.5, 5.0, 10.0, 15.0, 25.0, and 50.0 milligrams of the active ingredient for the symptomatic adjustment of the dosage to the patient to be treated. An effective amount of the drug is ordinarily supplied at a dosage level of from about 0.0001 mg/kg to about 100 mg/kg of body weight per day. The range is more particularly from about 0.001 mg/kg to 10 mg/kg of body weight per day. The dosages of the protease T modulators are adjusted when combined to achieve desired effects. On the other hand, dosages of these various agents may be independently optimized and combined to achieve a synergistic result wherein the pathology is reduced more than it would be if either agent were used alone.
Advantageously, compounds or modulators of the present invention may be administered in a single daily dose, or the total daily dosage may be administered in divided doses of two, three or four times daily. Furthermore, compounds or modulators for the present invention can be administered in intranasal form via topical use of suitable intranasal vehicles, or via transdermal routes, using those forms of transdermal skin patches well known to those of ordinary skill in that art. To be administered in the form of a transdermal delivery system, the dosage administration will, of course, be continuous rather than intermittent throughout the dosage regimen.
For combination treatment with more than one active agent, where the active agents are in separate dosage formulations, the active agents can be administered concurrently, or they each can be administered at separately staggered times.
The dosage regimen utilizing the compounds or modulators of the present invention is selected in accordance with a variety of factors including type, species, age, weight, sex and medical condition of the patient; the severity of the condition to be treated; the route of administration; the renal and hepatic function of the patient; and the particular compound thereof employed. A physician or veterinarian of ordinary skill can readily determine and prescribe the effective amount of the drug required to prevent, counter or arrest the progress of the condition. Optimal precision in achieving concentrations of drug within the range that yields efficacy without toxicity requires a regimen based on the kinetics of the drug's availability to target sites. This involves a consideration of the distribution, equilibrium, and elimination of a drug.
In the methods of the present invention, the compounds or modulators herein described in detail can form the active ingredient, and are typically administered in admixture with suitable pharmaceutical diluents, excipients or carriers (collectively referred to herein as “carrier” materials) suitably selected with respect to the intended form of administration, that is, oral tablets, capsules, elixirs, syrups and the like, and consistent with conventional pharmaceutical practices.
For instance, for oral administration in the form of a tablet or capsule, the active drug component can be combined with an oral, non-toxic pharmaceutically acceptable inert carrier such as ethanol, glycerol, water and the like. Moreover, when desired or necessary, suitable binders, lubricants, disintegrating agents and coloring agents can also be incorporated into the mixture. Suitable binders include, without limitation, starch, gelatin, natural sugars such as glucose or beta-lactose, corn sweeteners, natural and synthetic gums such as acacia, tragacanth or sodium alginate, carboxymethylcellulose, polyethylene glycol, waxes and the like. Lubricants used in these dosage forms include, without limitation, sodium oleate, sodium stearate, magnesium stearate, sodium benzoate, sodium acetate, sodium chloride and the like. Disintegrators include, without limitation, starch, methyl cellulose, agar, bentonite, xanthan gum and the like.
For liquid forms the active drug component can be combined in suitably flavored suspending or dispersing agents such as the synthetic and natural gums, for example, tragacanth, acacia, methyl-cellulose and the like. Other dispersing agents that may be employed include glycerin and the like. For parenteral administration, sterile suspensions and solutions are desired. Isotonic preparations, which generally contain suitable preservatives, are employed when intravenous administration is desired.
Topical preparations containing the active drug component can be admixed with a variety of carrier materials well known in the art, such as, eg., alcohols, aloe vera gel, allantoin, glycerine, vitamin A and E oils, mineral oil, PPG2 myristyl propionate, and the like, to form, eg., alcoholic solutions, topical cleansers, cleansing creams, skin gels, skin lotions, and shampoos in cream or gel formulations.
The compounds or modulators of the present invention can also be administered in the form of liposome delivery systems, such as small unilamellar vesicles, large unilamellar vesicles and multilamellar vesicles. Liposomes can be formed from a variety of phospholipids, such as cholesterol, stearylamine or phosphatidylcholines.
Compounds of the present invention may also be delivered by the use of monoclonal antibodies as individual carriers to which the compound molecules are coupled. The compounds or modulators of the present invention may also be coupled with soluble polymers as targetable drug carriers. Such polymers can include polyvinyl-pyrrolidone, pyran copolymer, polyhydroxypropylmethacryl-amidephenol, polyhydroxy-ethylaspartamidephenol, or polyethyl-encoxidepolylysine substituted with palmitoyl residues. Furthermore, the compounds or modulators of the present invention may be coupled to a class of biodegradable polymers useful in achieving controlled release of a drug, for example, polylactic acid, polyepsilon caprolactone, polyhydroxy butyric acid, polyorthoesters, polyacetals, polydihydro-pyrans, polycyanoacrylates and cross-linked or amphipathic block copolymers of hydrogels.
For oral administration, the compounds or modulators may be administered in capsule, tablet, or bolus form or alternatively they can be mixed in the animals feed. The capsules, tablets, and boluses are comprised of the active ingredient in combination with an appropriate carrier vehicle such as starch, talc, magnesium stearate, or di-calcium phosphate. These unit dosage forms are prepared by intimately mixing the active ingredient with suitable finely-powdered inert ingredients including diluents, fillers, disintegrating agents, and/or binders such that a uniform mixture is obtained. An inert ingredient is one that will not react with the compounds or modulators and which is non-toxic to the animal being treated. Suitable inert ingredients include starch, lactose, talc, magnesium stearate, vegetable gums and oils, and the like. These formulations may contain a widely variable amount of the active and inactive ingredients depending on numerous factors such as the size and type of the animal species to be treated and the type and severity of the infection. The active ingredient may also be administered as an additive to the feed by simply mixing the compound with the feedstuff or by applying the compound to the surface of the feed. Alternatively the active ingredient may be mixed with an inert carrier and the resulting composition may then either be mixed with the feed or fed directly to the animal. Suitable inert carriers include corn meal, citrus meal, fermentation residues, soya grits, dried grains and the like. The active ingredients are intimately mixed with these inert carriers by grinding, stirring, milling, or tumbling such that the final composition contains from 0.001 to 5% by weight of the active ingredient.
The compounds or modulators may alternatively be administered parenterally via injection of a formulation consisting of the active ingredient dissolved in an inert liquid carrier. Injection may be either intramuscular, intraruminal, intratracheal, or subcutaneous. The injectable formulation consists of the active ingredient mixed with an appropriate inert liquid carrier. Acceptable liquid carriers include the vegetable oils such as peanut oil, cottonseed oil, sesame oil and the like as well as organic solvents such as solketal, glycerol formal and the like. As an alternative, aqueous parenteral formulations may also be used. The vegetable oils are the preferred liquid carriers. The formulations are prepared by dissolving or suspending the active ingredient in the liquid carrier such that the final formulation contains from 0.005 to 10% by weight of the active ingredient.
Topical application of the compounds or modulators is possible through the use of a liquid drench or a shampoo containing the instant compounds or modulators as an aqueous solution or suspension. These formulations generally contain a suspending agent such as bentonite and normally will also contain an antifoaming agent. Formulations containing from 0.005 to 10% by weight of the active ingredient are acceptable. Preferred formulations are those containing from 0.01 to 5% by weight of the instant compounds or modulators.
Proteases are used in non-natural environments for various commercial purposes including laundry detergents, food processing, fabric processing, and skin care products. In laundry detergents, the protease is employed to break down organic, poorly soluble compounds to more soluble forms that can be more easily dissolved in detergent and water. In this capacity the protease acts as a “stain remover.” Examples of food processing include tenderizing meats and producing cheese. Proteases are used in fabric processing, for example, to treat wool in order prevent fabric shrinkage. Proteases may be included in skin care products to remove scales on the skin surface that build up due to an imbalance in the rate of desquamation. Common proteases used in some of these applications are derived from prokaryotic or eukaryotic cells that are easily grown for industrial manufacture of their enzymes, for example a common species used is Bacillus as described in U.S. Pat. No. 5,217,878. Alternatively, U.S. Pat. No. 5,278,062 describes serine proteases isolated from a fungus, Tritirachium album, for use in laundry detergent compositions. Unfortunately use of some proteases is limited by their potential to cause allergic reactions in sensitive individuals or by reduced efficiency when used in a non-natural environment. It is anticipated that protease proteins derived from non-human sources would be more likely to induce an immune response in a sensitive individual. Because of these limitations, there is a need for alternative proteases that are less immunogenic to sensitive individuals and/or provides efficient proteolytic activity in a non-natural environment. The advent of recombinant technology allows expression of any species' proteins in a host suitable for industrial manufacture.
Another aspect of the present invention relates to compositions comprising the Protease T and an acceptable carrier. The composition may be any variety of compositions that requires a protease component. Particularly preferred are compositions that may come in contact with humans, for example, through use or manufacture. The use of the Protease T of the present invention is believed to reduce or eliminate the immunogenic response users and/or handlers might otherwise experience with a similar composition containing a known protease, particularly a protease of non-human origin. Preferred compositions are skin care compositions and laundry detergent compositions.
Herein, “acceptable carries” includes, but is not limited to, cosmetically-acceptable carriers, pharmaceutically-acceptable carriers, and carriers acceptable for use in cleaning compositions.
Skin Care Compositions
Skin care compositions of the present invention preferably comprise, in addition to the Protease T, a cosmetically- or pharmaceutically acceptable carrier.
Herein, “cosmetically-acceptable carrier” means one or more compatible solid or liquid filler diluents or encapsulating substances which are suitable for use in contact with the skin of humans and lower animals without undue toxicity, incompatibility, instability, irritation, allergic response, and the like, commensurate with a reasonable benefit/risk ratio.
Herein, “pharmaceutically-acceptable” means one or more compatible drugs, medicaments or inert ingredients which are suitable for use in contact with the tissues of humans and lower animals without undue toxicity, incompatibility, instability, irritation, allergic response, and the like, commensurate with a reasonable. benefit/risk ratio. Pharmaceutically-acceptable carriers must, of course, be of sufficiently high purity and sufficiently low toxicity to render them suitable for administration to the mammal being treated.
Herein, “compatible” means that the components of the cosmetic or pharmaceutical compositions are capable of being commingled with the Protease T, and with each other, in a manner such that there is no interaction which would substantially reduce the cosmetic or pharmaceutical efficacy of the composition under ordinary use situations.
Preferably the skin care compositions of the present invention are topical compositions, i.e., they are applied topically by the direct laying on or spreading of the composition on skin. Preferably such topical compositions comprise a cosmetically- or pharmaceutically-acceptable topical carrier.
The topical composition may be made into a wide variety of product types. These include, but are not limited to, lotions, creams, beach oils, gels, sticks, sprays, ointments, pastes, mousses, and cosmetics; hair care compositions such as shampoos and conditioners (for, e.g., treating/preventing dandruff); and personal cleansing compositions. These product types may comprise several carrier systems including, but not limited to, solutions, emulsions, gels and solids.
Preferably the carrier is a cosmetically- or pharmaceutically-acceptable aqueous or organic solvent. Water is a preferred solvent. Examples of suitable organic solvents include: propylene glycol, polyethylene glycol (200-600), polypropylene glycol (425-2025), propylene glycol-14 butyl ether, glycerol, 1,2,4butanetriol, sorbitol esters, 1,2,6-hexanetriol, ethanol, isopropanol, butanediol, and mixtures thereof. Such solutions useful in the present invention preferably contain from about 0.001% to about 25% of the Protease T, more preferably from about 0.1% to about 10% more preferably from about 0.5% to about 5%; and preferably from about 50% to about 99.99% of an acceptable aqueous or organic solvent, more preferably from about 90% to about 99%.
Skin care compositions of the present invention may further include a wide variety of additional oil-soluble materials and/or water-soluble materials conventionally used in topical compositions, at their art-established levels. Such additional components include, but are not limited to: thickeners, pigments, fragrances, humectants, proteins and polypeptides, preservatives, pacifiers, penetration enhancing agents, collagen, hylauronic acid, elastin, hydrolysates, primrose oil, jojoba oil, epidermal growth factor, soybean saponins, mucopolysaccharides, Vitamin A and derivatives thereof, Vitamin B2, biotin, pantothenic acid, Vitamin D, and mixtures thereof.
Cleaning compositions of the present invention preferably comprise, in addition to the Protease T, a surfactant. The cleaning composition may be in a wide variety of forms, including, but not limited to, hard surface cleaning compositions, dishcare cleaning compositions, and laundry detergent compositions.
Preferred cleaning compositions are laundry detergent compositions. Such laundry detergent compositions include, but not limited to, granular, liquid and bar compositions. Preferably, the laundry detergent composition further comprises a builder.
The laundry detergent composition of the present invention contains the Protease T at a level sufficient to provide a “cleaning-effective amount”. The term “cleaning effective amount” refers to any amount capable of producing a cleaning, stain removal, soil removal, whitening, deodorizing, or freshness improving effect on substrates such as fabrics, dishware and the like. In practical terms for current commercial preparations, typical amounts are up to about 5 mg by weight, more typically 0.01 mg to 3 mg, of active enzyme per gram of the detergent composition. Stated another way, the laundry detergent compositions herein will typically comprise from 0.001% to 5%, preferably 0.01%-3%, more preferably 0.01% to 1% by weight of raw Protease T preparation. Herein, “raw Protease T preparation” refers to preparations or compositions in which the Protease T is contained in prior to its addition to the laundry detergent composition. Preferably, the Protease T is present in such raw Protease T preparations at levels sufficient to provide from 0.005 to 0.1 Anson units (AU) of activity per gram of raw Protease T preparation. For certain detergents, such as in automatic dishwashing, it maybe desirable to increase the active Protease T content of the raw Protease T preparation in order to minimize the total amount of non-catalytically active
Materials and thereby improve spotting/filming or other end-results. Higher active levels may also be desirable in highly concentrated detergent formulations.
Preferably, the laundry detergent compositions of the present invention, including but not limited to liquid compositions, may comprise from about 0.001% to about 10%, preferably from about 0.005% to about 8%, most preferably from about 0.01% to about 6%, by weight of an enzyme stabilizing system. The enzyme stabilizing system can be any stabilizing system that is compatible with the Protease T, or any other additional detersive enzymes that may be included in the composition. Such a system may be inherently provided by other formulation actives, or be added separately, e.g., by the formulator or by a manufacturer of detergent-ready enzymes. Such stabilizing systems can, for example, comprise calcium ion, boric acid, propylene glycol, short chain carboxylic acids, boronic acids, and mixtures thereof, and are designed to address different stabilization problems depending on the type and physical form of the detergent composition.
The detergent composition also comprises a detersive surfactant. Preferably the detergent composition comprises at least about 0.01% of a detersive surfactant; more preferably at least about 0.1%; more preferably at least about 1%; more preferably still, from about 1% to about 55%.
Preferred detersive surfactants are cationic, anionic, nonionic, ampholytic, zwifterionic, and mixtures thereof, further described herein below. Nonlimiting examples of detersive surfactants useful in the detergent composition include, the conventional C11-C18 alkyl benzene sulfonates (“LAS”) and primary, branched-chain and random C10-C20 alkyl sulfates (“AS”), the C10-C18 secondary (2,3) alkyl sulfates of the formula CH3(CH2)x(CHOSO3—M+) CH3 and CH3 (CH2)y(CHOSO3—M+) CH2CH3 where x and (y+1) are integers of at least about 7, preferably at least about 9, and M is a water-solubilizing cation, especially sodium, unsaturated sulfates such as oleyl sulfate, the C10-C18 alkyl alkoxy sulfates (“AExS”; especially EO 1-7 ethoxy sulfates), C10-C18 alkyl alkoxy carboxylates (especially the EO 1-5 ethoxycarboxylates), the C10-C18 glycerol ethers, the C10-C18 alkyl polyglycosides and their corresponding sulfated polyglycosides, and C12-C18 alpha-sulfonated fatty acid esters. If desired, the conventional nonionic and amphoteric surfactants such as the C12-C18 alkyl ethoxylates (“AE”) including the so-called narrow peaked alkyl Ethoxylates and C6-C12 alkyl phenol alkoxylates (especially ethoxylates and mixed ethoxy/propoxy), C12-C18 betaines and solfobetaines (“sultaines”), C10-C18 amine oxides, and the like, can also be included in the overall compositions. The C10-C18 N-alkyl polyhydroxy fatty acid amides can also be used. Typical examples include the C12-C18 N-methylglucamides. See WO 9,206,154. Other sugar-derived surfactants include the N-alkoxy polyhydroxy fatty acid amides, such as C10-C18 N-(3-methoxypropyl) glucamide. The N-propyl through N-hexyl C12-C18 glucamides can be used for low sudsing. C10-C20 conventional soaps may also be used. If high sudsing is desired, the branched-chain C10-C16 soaps may be used. Mixtures of anionic and nonionic surfactants are especially useful. Other conventional useful surfactants are listed in standard texts.
Detergent builders are also included in the laundry detergent composition to assist in controlling mineral hardness. Inorganic as well as organic builders can be used. Builders are typically used in fabric laundering compositions to assist in the removal of particulate soils.
The level of builder can vary widely depending upon the end use of the composition and its desired physical form. When present, the compositions will typically comprise at least about 1% builder. Liquid formulations typically comprise from about 5% to about 50%, more typically about 5% to about 30%, by weight, of detergent builder. Granular formulations typically comprise from about 10% to about 80%, more typically from about 15% to about 50% by weight, of the detergent builder. Lower or higher levels of builder, however, are not meant to be excluded.
Inorganic or P-containing detergent builders include, but are not limited to, the alkali metal, ammonium and alkanolammonium salts of polyphosphates (exemplified by the tripolyphosphates, pyrophosphates, and glassy polymeric meta-phosphates), phosphonates, phytic acid, silicates, carbonates (including bicarbonates and sesquicarbonates), sulphates, and aluminosilicates. However, non-phosphate builders are required in some locales. Importantly, the compositions herein function surprisingly well even in the presence of the so-called “weak” builders (as compared with phosphates) such as citrate, or in the so-called “underbuilt” situation that may occur with zeolite or layered silicate builders.
Examples of silicate builders are the alkali metal silicates, particularly those having a SiO2:Na2O ration in the range 1.6:1 to 3.2:1 and layered silicates, such as the layered sodium silicates described in U.S. Pat. No. 4,664,839, issued May 12, 1987 to H. P. Rieck. NaSKS-6 is the trademark for a crystalline layered silicate marketed by Hoechst (commonly abbreviated herein as “SKS-6”). Unlike zeolite builders, the Na SKS-6 silicate builder does not contain aluminum. NaSKS-6 has the delta-Na2SiO5 morphology form of layered silicate. It can be prepared by methods such as those described in German DE-A-3,417,649 and DE-A-3,742,043. SKS-6 is a highly preferred layered silicate for use herein, but other such layered silicates, such as those having the general formula NaMSixO2x+1yH2O wherein M is sodium or hydrogen, x is a number from 1.9 to 4, preferably 2, and y is a number from 0 to 20, preferably 0 can be used herein. Various other layered silicates from Hoechst include NaSKS-5, NaSKS-7 and NaSKS-11, as the alpha, beta and gamma forms. As noted above, the delta-Na2SiO5 (NaSKS-6 form) is most preferred for use herein. Other silicates may also be useful such as for example magnesium silicate, which can serve as a crispening agent in granular formulations, as a stabilizing agent for oxygen bleaches, and as a component of suds control systems.
Examples of carbonate builders are the alkaline earth and alkali metal carbonates as disclosed in German Patent Application No. 2,321,001 published on Nov. 15, 1973.
Aluminosilicate builders are useful in the present invention. Aluminosilicate builders are of great importance in most currently marketed heavy duty granular detergent compositions, and can also be a significant builder ingredient in liquid detergent formulations. Aluminosilicate builders include those having the empirical formula:
Useful aluminosilicate ion exchange materials are commercially available. These aluminosilicates can be crystalline or amorphous in structure and can be naturally-occurring aluminosilicates or synthetically derived. A method for producing aluminosilicate ion exchange materials is disclosed in U.S. Pat. No. 3,985,669, Krummel, et al, issued Oct. 12, 1976. Preferred synthetic crystalline aluminosilicate ion exchange materials useful herein are available under the designations Zeolite A, Zeolite P (b), Zeolite MAP and Zeolite X. In an especially preferred embodiment, the crystalline aluminosilicate ion exchange material has the formula:
Organic detergent builders suitable for the purposes of the present invention include, but are not restricted to, a wide variety of polycarboxylate compounds. As used herein, “polycarboxylate” refers to compounds having a plurality of carboxylate groups, preferably at least 3 carboxylates. Polycarboxylate builder can generally be added to the composition in acid form, but can also be added in the form of a neutralized salt. When utilized in salt form, alkali metals, such as sodium, potassium, and lithium, or alkanolammonium salts are preferred.
Included among the polycarboxylate builders are a variety of categories of useful materials. One important category of polycarbonate builders encompasses the ether polycarboxylates, including oxydisuccinate, as disclosed in Berg, U.S. Pat. No. 3,128,287, issued Apr. 7, 1964, and Lamberti et al., U.S. Pat. No. 3,635,830, issued Jan. 18, 1972. See also “TMSFTDS” builders of U.S. Pat. No. 4,663,071, issued to Bush et al., on May 5, 1987. Suitable ether polycarboxylates also include cyclic compounds, particularly alicyclic compounds, such as those described in U.S. Pat. No. 3,923,679 to Rapko, issued Dec. 2, 1975; U.S. Pat. No. 3,835,163 to Rapko, issued Sep. 10, 1974; U.S. Pat. No. 4,158,635 to Crutchfield et al., issued Jun. 19, 1979; U.S. Pat. No. 4,120,874 to Crutchfield et al., issued Oct. 17, 1978; and U.S. Pat. No. 4,102,903 to Crutchfield et al., issued Jul. 25, 1978.
Other useful detergency builders include the ether hydroxypolycarboxylates, copolymers of maleic anhydride with ethylene or vinyl methyl ether, 1,3,5-trihydroxy benzene-2,4,6-t6sulphonic acid, and carboxymethyloxysuccinic acid, the various alkali metal, ammonium and substituted ammonium salts of polyacetic acids such as. ethylenediamine tetraacetic acid and nitrilotriacetic acid, as well as polycarboxylates such as Mellitic acid, succinic acid, oxydisuccinic acid, polymaleic acid, benzene 1,3,5-tricarboxylic acid, carboxymethyloxysuccinic acid, and soluble salts thereof, citrate builders, e.g., citric acid and soluble salts thereof (particularly sodium salt), are polycarboxylate builders of particular importance for heavy-duty liquid detergent formulations due to their availability from renewable resources and their biodegradability. Citrates can also be used in granular compositions, especially in combination with zeolite and/or layered silicate builders. Oxydisuccinates are also especially useful in such compositions and combinations.
Also suitable in the detergent compositions of the present invention are the 3,3-dicarboxy-4-oxa-1,6-hexanedioates and the related compounds disclosed in U.S. Pat. No. 4,566,984 to Bush, issued Jan. 28, 1986. Useful succinic acid builders include the C5-C20 alkyl and alkenyl succinic acids and salts thereof. A particularly preferred compound of this type is dodecenylsuccinic acid. Specific examples of succinate builders include: laurylsuccinate, myristylsuccinate, paimitylsuccinate, 2-dodecenylsuccinate (preferred), 2pentadecenylsuccinate, and the like. Lauryisuccinates are the preferred builders of this group, and are described in European Patent Application 200,263 to Barrat et al., published Nov. 5, 1986.
Other suitable polycarboxylates are disclosed in U.S. Pat. No. 4,144,226, Crutchfield et al, issued Mar. 13, 1979 and in U.S. Pat. No. 3,308,067, Diehl, issued Mar. 7, 1967. See also U.S. Pat. No. 3,723,322 to Diehl, issued Mar. 27, 1973.
Fatty acids, e.g., C12-C18 monocarboxylic acids, can also be incorporated into the compositions alone, or in combination with the aforesaid builders, especially citrate and/or the succinate builders, to provide additional builder activity. Such use of fatty acids will generally result in a diminution of sudsing, which should be taken into account by the formulator.
In situations where phosphorus-based builders can be used, and especially in the formulation of bars used for hand-laundering operations, the various alkali metal phosphates such as the well-known sodium tripolyphosphates, sodium pyrophosphate and sodium orthophosphate can be used. Phosphonate builders such as ethane-1-hydroxy-1,1-diphosphonate and other known phosphonates (see, for example, U.S. Pat. No. 3,159,581 to Diehl, issued Dec. 1, 1964; U.S. Pat. No. 3,213,030 to Diehl, issued Oct. 19, 1965; U.S. Pat. No. 3,400,148 to Quimby, issued Sep. 3, 1968; U.S. Pat. No. 3,422,021 to Roy, issued Jan. 14, 1969; and U.S. Pat. No. 3,422,137 to Quimby, issued Jan. 4, 1969) can also be used.
Additional components which may be used in the laundry detergent compositions of the present invention include, but are not limited to: alkoxylated polycarboxylates (to provide, e.g., additional grease stain removal performance), bleaching agents, bleach activators, bleach catalysts, brighteners, chelating agents, clay soil removal/anti-redeposition agents, dye transfer inhibiting agents, additional enzymes (including lipases, amylases, hydrolases, and other proteases), fabric softeners, polymeric soil release agents, polymeric dispersing agents, and suds suppressors,
The compositions herein may further include one or more other detergent adjunct materials or other materials for assisting or enhancing cleaning performance, treatment of the substrate to be cleaned, or to modify the aesthetics of the detergent composition (e.g., perfumes, colorants, dyes, etc.).
The detergent compositions herein may further comprise other known detergent cleaning components including alkoxylated polycarboxylates, bleaching compounds, brighteners, chelating agents, clay soil removal/antiredeposition agents, dye transfer inhibiting agents, enzymes, enzyme stabilizing systems, fabric softeners, polymeric soil release agents, polymeric dispersing agents, suds suppressors. The detergent composition may also comprise other ingredients including carriers, hydrotropes, processing aids, dyes or pigments, solvents for liquid formulations, solid fillers for bar compositions.
Method of Treating or Preventing Skin Flaking
Another aspect of the present invention relates to a method of treating or preventing skin flaking. The method comprises topical application of a safe and effective amount of a composition comprising the Protease T.
Herein, “safe and effective amount” means an amount of Protease T high enough to provide a significant positive modification of the condition to be treated, but low enough to avoid serious side effects (at a reasonable benefit/risk ratio), within the scope of sound medical judgment. A safe and effective amount of Protease T will vary with the particular condition being treated, the age and physical condition of the subject being treated, the severity of the condition, the duration of the treatment, the nature of concurrent therapy and like factors.
Suitable compositions for use in the subject method include the above-described skin care compositions, including hair care compositions (for example, treating/preventing dandruff caused by skin flaking.
The following examples illustrate the present invention without, however, limiting the same thereto.
All molecular biological methods were in accordance with those previously described (Maniatis et al. (1989). 1-1626). Oligonucleotides were purchased from Ransom Hill Biosciences (Ransom Hill, Calif.) and all restriction endonucleases and other DNA modifying enzymes were from New England Biolabs (Beverly, Mass.) unless otherwise specified. The protease T expression construct was made in the Drosophila inducible expression vector pRM64, featuring a constitutive actin promoter as described below. The Drosophila expression vectors used are similar to those commercially available (Invitrogen, San Diego, Calif.). All construct manipulations were confirmed by dye terminator cycle sequencing using Allied Biosystems 377 fluorescent sequencers (Perkin Elmer, Foster City, Calif.).
Acquisition of Protease T cDNA
Library was constructed using 2 micrograms of polyA RNA isolated from esophageal tissue removed from a 53-year-old Caucasian male during a partial esophagectomy, proximal gastrectomy, and regional lymph node biopsy. The cDNA synthesis was initiated using a NotI-oligo(dT) primer and double-stranded cDNA was blunted, ligated to EcoRI adaptors, digested with NotI, size-selected, and cloned into the NotI and EcoRI sites of a modified plasmid cloning vector. A clone, corresponding to the full-length protease T cDNA, contained an open reading frame of 873 nucleotides (including the stop codon, FIG. 1), and had homology to other S1 serine proteases. This clone is also likely to contain the entire 3′ untranslated region since an AATAAA motif resides 22 nucleotides upstream of a poly A stretch. Homology searches of the Genbank database with the protease T cDNA indicated that this was a novel cDNA but had identity with the human cosmid clone (400D1, Genbank accession #AC004036), which maps to chromosome 16p13.3, indicating the position of protease T gene. The deduced open reading frame encodes a preproprotease T protein of 290 amino acids (FIG. 1), with an estimated molecular mass (Mr) of about 32-Kd, and a strong homology to other serine proteases. The catalytic triad residues H, D and S are located at positions 75, 124 and 229, respectively. The zymogen activation sequence is similar to that of other S1 serine proteases and predicts a mature protein of 256 amino acids. A signal peptide of 23 amino acids is predicted by statistical method (Von Heijne (1986). Nucleic Acids Res. 14:4683-90) indicating a pre-sequence peptide of 12 amino acids. A phylogenetic tree of an alignment of the deduced protease T amino acid sequence with other members of the S1 serine protease family is shown in
Tissue Distribution of Protease T mRNA
We employed a highly sensitive PCR profiling technique to identify the tissue distribution of protease T mRNA. For this application, human cDNA libraries were from Clontech, (Palo Alto, Calif.). The PCR primers for the profiling analysis were as follows:
The 50 μl PCR reactions used 1 μl of diluted phage stock (˜108 to 1010 pfu/ml) from each of the cDNA libraries tested. Reactions were initially denatured at 94° C. for 5 minutes and subjected to 35 cycles of 94° C. for 20 seconds; 56° C. for 20 seconds; and then 72° C. for 30 seconds followed by a final 72° C. elongation for 10 minutes A nested primer probe of the sequence
As seen in
Construct Generation for the Expression of Active Protease T
Since members of the S1 protease family are most often synthesized as inactive zymogen precursors, and require limited proteolysis to become proteolytically active, we have developed a zymogen activation construct to express and permit the generic activation of heterologous serine protease cDNAs. This construct features a bovine preprolactin signal sequence fused in-frame with the MoAb M2 anti-FLAG antibody epitope as previously described (Ishii et al. (1 993). J. Biol. Chem. 268:9780-6) for the purposes of secretion and antibody detection respectively (PF). Significantly, this construct also contains the enterokinase cleavage site from human trypsinogen I (EK) fused in-frame and downstream from the signal sequence. At the C-terminus, preceding a stop codon, are additional sequences encoding 6 histidine (6XHIS) codons for affinity purification on nickel resins respectively. A unique Xba I restriction enzyme site, immediately upstream of the 6XHIS affinity tag sequence and downstream of the PFEK prepro sequence described above, and is the point of in-frame insertion of the catalytic domain of a heterologous serine protease cDNA (FIG. 4). The zymogen activation vector described above has been cloned into a modified Drosophila expression plasmid to generate PFEK-6XHIS-TAG64.
The purified plasmid DNA of the full length protease T cDNA was used as a template in a 100 μl preparative PCR reaction using the Advantage-GC cDNA Polymerase Mix (Clontech, Palo Alto, Calif.) in accordance with the manufacturer's recommendations. The primers used
The preparative PCR product was phenol/CHCl3 (1:1) extracted once, CHCl3 extracted, and then EtOH precipitated with glycogen (Boehringer Mannheim Corp., Indianapolis, Ind.) and carrier. The precipitated pellet was rinsed with 70% EtOH, dried by vacuum, and resuspended in 80 ul H2O, 10 ul 10×restriction buffer number 2 and 1 ul 100×BSA (New England Biolabs, Beverly, Mass.). The product was digested for 3 hours at 37° C. with 200 units Xba I restriction enzyme (New England Biolabs, Beverly, Mass.). The Xba I digested product was phenol/CHCl3 (1:1) extracted once, CHCl3 extracted, EtOH precipitated, rinsed with 70% ETOH, and dried by vacuum. For purification from contaminating template plasmid DNA, the product was electrophoresed through 1.0% low melting temperature agarose (Life Technologies, Gaithersberg, Md.) gels in TAE buffer (40 mM Tris-Acetate, 1 mM EDTA pH 8.3) and excised from the gel. An aliquot of the excised product was then used for in-gel ligations with the Xba I digested, dephosphorylated and gel purified, zymogen activation vector described above. Clones containing the protease T Xba cassette, inserted in the correct orientation to generate the construct PFEK-protease T-6XHIS-TAG64, were confirmed by sequence analyses to ensure that the proper translational register with respect to the NH2-terminal PFEK prepro sequence and C-terminal 6XHIS affinity tag was maintained.
Expression of Recombinant Protease T
The recombinant baculovirus containing the PFEK-protease T-HA6XHIS construct was prepared from bacterial transformation, selection, growth, purification and PCR confirmation in accordance with the manufacturer's recommendations. Cultured Sf9 insect cells (ATCC CRL-1711) were transfected with purified bacmid DNA and several days later, conditioned media containing recombinant PFEK-protease T-HA6XHIS baculovirus was used to infect fresh Sf9 cells. Infected cells were incubated at 24 to 27° C. for 48 hours and conditioned media used to purify the recombinant PFEK-protease T-HA6XHIS zymogen.
Purification, and Activation of Recombinant Protease T
The conditioned medium from infected Sf9 cells was used to purify secreted recombinant PFEK-protease T-HA6XHIS zymogen. The medium was concentrated 5 to 10 fold using a Centriprep concentrator (Amicon Inc., Beverly, Mass.). 150 μl of a 50% Ni-NTA slurry (Qiagen, Valencia, Calif.) was added to 5 to 10 ml of the concentrated medium and mixed by shaking at 4° C. for 60 minutes. The zymogen-bound resin was washed 3 times with 1.5 ml of wash buffer (10 mM Tris-HCl (pH 8.0), 300 mM NaCl, and 15 mM imidazole,), followed by with a 1.5 ml wash with ds H2O. Enterokinase cleavage was carried out by adding enterokinase (Novagen, Inc., Madison Wis.; or Sigma, St. Louis, Mo.) to the zymogen-bound Ni-NTA beads in a 150 ul volume at room temperature overnight with gentle shaking in a buffer containing 20 mM Tris-HCl (pH 7.4), 50 mM NaCl, and 2.0 mM CaCl2. The resin was then washed twice with 1.5 ml wash buffer. The activated protease T-HA6XHIS was eluted with elution buffer (20 mM Tris-HCl (pH 7.8), 250 mM NaCl, and 250 mM imidazole). Eluted protein concentration was determined by a Micro BCA Kit (Pierce, Rockford, Ill.) using bovine senim albumin as a standard. Amidolytic activities of the activated protease T-HA6XHIS was monitored by release of para-nitroaniline (pNA) from the synthetic substrates indicated in Table 1 and FIG. 6. The chromogenic substrates used in these studies were all commercially available (Bachem California Inc., Torrance, Pa.; American Diagnostica Inc., Greenwich, Conn.; Kabi Pharmacia Hepar Inc., Franklin, Ohio). Assay mixtures contained chromogenic substrates at 500 uM and 10 mM Tris-HCl (pH 7.8), 25 mM NaCl, and 25 mM imidazole. Release of pNA was measured over 120 minutes at 37° C. on a micro-plate reader (Molecular Devices, Menlo Park, Calif.) with a 405 nm absorbance filter. The initial reaction rates (Vmax, mOD/min) were determined from plots of absorbance versus time using Softmax (Molecular Devices, Menlo Park, Calif.). The specific activities (nmole pNA produced /min/ug protein) of the activated protease T-HA6XHIS for the various substrates are presented in Table 1. No measurable chromogenic amidolytic activity was detected with the purified unactivated PFEK-protease T-HA6XHIS zymogen.
Samples of the purified PFEK-protease T-6XHIS zymogen or activated protease T-6XHIS, were denatured in the presence of the reducing agent dithiothreitol (DTT), were analyzed by SDS-PAGE (Bio Rad, Hercules Calif.) stained with Coomassie Brilliant Blue. For Western blotting, gels were electrotransfer to Hybond ECL membranes (Amersham, Arlington Heights, Ill.). The FLAG-tagged PFEK protease T-6XHIS zymogen purified from transfected Drosophila cells was detected with anti-Flag M2 antibody (Babco, Richmond, Calif.). The secondary antibody was a goat-anti-mouse IgG (H+L), horseradish peroxidase-linked F(ab′)2 fragment, (Boehringer Mannheim Corp., Indianapolis, Ind.) and was detected by the ECL kit (Amersham, Arlington Heights, Ill.).
Polyacrylamide gel and Western blot analyses of the purified recombinant protease PFEK-protease T-6XHIS zymogen, and the activated protease T-6XHIS form following its expression using the activation construct of FIG. 4. Shown is the polyacrylamide gel containing samples of the novel serine protease PFEK-protease T-6XHIS stained with Coomassie Brilliant Blue (A.). The relative molecular masses are indicated by the positions of protein standards (M). In the indicated lanes, the purified zymogen was either untreated (−) or digested with EK (+) which was used to cleave and activate the zymogen into its active form. A Western blot of the gel in A, probed with the anti-FLAG MoAb M2, is also shown (B.). This demonstrates the quantitative cleavage of the expressed and purified zymogen to generate the processed and activated protease. Since the FLAG epitope is located just upstream of the of the EK pro sequence (FIG. 4), cleavage with EK generates a FLAG-containing polypeptide which is too small to be retained in the polyacrylamide gel, and is therefore not detected in the +EK lane.
Protease T Activity Assay
Amidolytic activities of the activated serine proteases are monitored by release of para-nitroaniline (pNA) from synthetic substrates that are commercially available (Bachem California Inc., Torrance, Pa.; American Diagnostica Inc., Greenwich, Conn.; Kabi Pharmacia Hepar Inc., Franklin, Ohio). Assay mixtures contain chromogenic substrates in 500 uM and 10 mM TRIS-HCl (pH 7.8), 25 mM NaCl, and 25 mM imidazole. Release of pNA is measured over 120 min at 37° C. on a micro-plate reader (Molecular Devices, Menlo Park, Calif.) with a 405 nm absorbance filter. The initial reaction rates (Vmax, mOD/min) are determined from plots of absorbance versus time using Softmax (Molecular Devices, Menlo Park, Calif.). Compounds that modulate a serine protease of the present invention are identified through screening for the acceleration, or more commonly, the inhibition of the proteolytic activity. Although in the present case chromogenic activity is monitored by an increase in absorbance, fluorogenic assays or other methods such as FRET to measure proteolytic activity as mentioned above, can be employed. Compounds are dissolved in an appropriate solvent, such as DMF, DMSO, methanol, and diluted in water to a range of concentrations usually not exceeding 100 uM and are typically tested, though not limited to, a concentration of 1000-fold the concentration of protease. The compounds are then mixed with the protein stock solution, prior to addition to the reaction mixture. Alternatively, the protein and compound solutions may be added independently to the reaction mixture, with the compound being added either prior to, or immediately after, the addition of the protease protein.